1. Field of the Invention
The present invention relates to a sewing machine and a recording medium for use in combination with the sewing machine.
2. Description of the Related Art
A conventional embroidering machine will be described hereinafter referring to FIG. 1. As shown in FIG. 1, this machine has a bed 10, a standard 12 rising from the right-hand end of the bed 10, an arm 14 horizontally extending over the bed 10 from the upper end of the standard 12, and a sewing head 16 formed on the extremity of the arm 14.
A liquid crystal display unit 20 of a dot matrix type is attached to the front wall of the arm 14. Pattern selection keys, and a selected pattern and stitching position changing key are displayed on the screen of the display unit 20. An analog transparent electrode switch plate 22 is put on the front surface of the display 20. Keys displayed on the screen of the display unit 20 can be operated. Operating keys 24 for selecting types of patterns are arranged on the front wall of the arm 14 in a region on the right-hand side of the display unit 20.
A start-stop switch 26 for starting and stopping stitching operation is attached to the front wall of the sewing head 16. A needle bar 30 is supported for vertical reciprocation on the sewing head 16 so as to project downward from the lower end of the sewing head 16, and a needle 32 is fixed to the lower end of the needle bar 30. A presser bar 34 is supported for movement between an upper position and a lower position on the sewing head 16 in parallel to the needle bar 30, and a presser foot 36 is fixed to the lower end of the presser bar 34.
An embroidering unit 37 is mounted on the bed 10. The embroidering unit 37 has an embroidery frame moving mechanism 39 mounted on the upper wall thereof. The embroidery frame moving mechanism 39 moves an embroidery frame 38 holding the workpiece longitudinally and laterally relative to the needle 32.
Each of the embroidery patterns to be stitched by the embroidering machine has a reference point 40 with respect to which the embroidery pattern is stitched, i.e., the position of each stitch in the embroidery pattern is defined relative to the reference point 40. The reference point 40 of, for example, a pattern as shown in FIG. 2 may be at the intersection point of the longitudinal and lateral center lines, i.e., alternate long and short dash lines in FIG. 2, of a rectangular pattern frame 44 circumscribing the pattern. The rectangular pattern frame 44 circumscribing the embroidery pattern is preferably a rectangle (which may be a square) which is of the minimum area required to circumscribe the embroidery pattern. The reference point can be located at any desired location relative to the embroidery pattern, e.g., in some instances, it might be desired to have the reference point 40 displaced from the center of the pattern 42 or even outside the oval shape of the pattern 42. When the push button of the start-stop switch 26 is pushed, the pattern 42 is embroidered so that the reference point 40 thereof is directly below the position where the needle 32 was located at a time (1) before the first stitch in the stitching pattern was stitched, and (2) when the push button was operated to start stitching the stitching pattern. Thus, with regard to the stitching pattern shown in FIG. 2, the needle 32 is located above the reference point 40 before the push button is pushed and before the first stitch in the stitching pattern is stitched.
Referring to FIG. 3 showing the embroidery frame 38 and the embroidery frame moving mechanism 39 of the embroidering unit 37 in an enlarged view, the embroidery frame 38 has a 10 cm .times.10 cm square effective embroidering area 52. A center position 50 is at the center of the effective embroidering area 52. When the main switch of the embroidering machine is closed to connect the embroidering machine to a power source, the embroidery frame 38 is positioned so that the center position 50 is directly below the needle 32.
Upon the completion of the embroidering of a pattern, the embroidering machine stops with the needle 32 at the end of the embroidered pattern or the thread is cut, and the embroidery frame 38 is returned automatically to its reference position relative to the needle 32, such that the reference point 40 of the embroidery pattern is again directly below the needle 32.
When successively embroidering patterns by using a ROM card storing pattern data, the embroidering machine stops with the needle 32 at the end of the embroidered pattern. If the embroidering machine is started after cutting the thread without changing the position of the needle 32 to embroider the next pattern, the next pattern is embroidered over the previously embroidered pattern with its .reference point on that of the previously embroidered pattern. The pattern data is prepared so that the patterns embroidered in successive embroidering cycles are superposed properly.
As shown in FIGS. 4A and 4B, the position of the pattern frame 44 in the effective embroidering area 52 of the embroidery frame 38 is determined by operating embroidery frame movement keys displayed on the screen of the display unit 20. For example, the pattern frame 44 positioned at the center of the effective embroidering area 52 as shown in FIG. 4A can be shifted to a lower position in the effective embroidering area 52 shown in FIG. 4B by operating the down key 60, i.e., one of the embroidery frame movement keys, such that the reference point 40 of the embroidery pattern differs from the center position 50. Thus, operation of the embroidery frame movement keys moves the location of the reference point 40 with respect to which the embroidery pattern is stitched. When the push button of the start-stop switch 26 is pushed with the pattern frame 44 positioned as shown in FIG. 4B, a selected pattern is embroidered in the pattern frame 44 positioned at the lower position shown in FIG. 4B. Thus, the position of the pattern frame 44 in the effective embroidering area 52 can be optionally determined by manual operation.